1. Field of the Invention
The present invention relates to a holder for holding a small-sized electronic part to be built in an apparatus (herein, referred to as “mounting object apparatus”) such as a mobile phone, a personal handy-phone system (PHS), or a personal digital assistant (PDA), examples of the small-sized electronic part including a microphone, a speaker, a receiver, a vibrator, a buzzer, and an electronic part which is a functional combination of those, and for electrically connecting electrodes of the small-sized electronic part to circuit electrodes of a board.
2. Description of the Related Art
As a technique for obtaining an electrical connection between electrodes of the small component and circuit electrodes of a board, there is known a technique using a holder for the small-sized electronic part, which is disclosed in JP 11-191469 A.
FIGS. 9A and 9B each show a conventional holder (1) for the small-sized electronic part. The holder (1) includes a cylindrical holding portion (2), a bottom portion (3) for closing one end side of the holding portion (2), and an annular pressing flange (4) protruding inwardly from the other end side of the holding portion (2). The holder (1) is a mold body formed of a soft rubber-like elastic material having electrical insulation properties such as silicone rubber. In this conventional example, in the bottom portion (3) of the holder (1), there are provided four elastic connector portions (5) thicker than the bottom portion (3). At a center of each of the elastic connector portions (5), a conduction path (5a) is formed. The conduction path (5a) is formed of fine granular magnetic conductive materials such as nickel grains. That is, the conduction path (5a) is formed by arranging the magnetic conductive materials, which is mixed in advance with liquid silicone rubber constituting a material resin of the holder (1), in a magnetic orientation along an axial direction of the conduction path (5a) during a molding process of the holder (1). A portion of the elastic connector portion (5) other than the conduction path (5a), that is, an outer peripheral portion (5b) is formed for retaining a shape of the conduction path (5a) and for stabilizing the electrical connection through the conduction path (5a).
The holder (1) is used, for example, for electrically connecting electrodes (6a, 6b) of the small-sized electronic part (6) and circuit electrodes (7a, 7b) of a board (7) provided to a mounting object apparatus such as a mobile phone shown in FIG. 10. To perform electrical connection, first, an inner edge of the pressing flange (4) is pressed to be widened, and then, the small-sized electronic part (6) is accommodated in the holding portion (2). Next, as shown in FIG. 11, the holder (1) accommodating the small-sized electronic part (6) is mounted to a mounting recess (8a) formed in an inner surface of a casing (8) of the mounting object apparatus (for example, mobile phone) by inserting in the mounting recess (8a). When the casing (8) is combined with another casing (not shown) or when the board (7) is fixed to the casing (8), the conduction path (5a) of the elastic connector portion (5) contacting with the electrodes (6a, 6b) of the small-sized electronic part (6) comes into contact with the circuit electrodes (7a, 7b) of the board (7). In this state, the pressing flange (4) functions to press the small-sized electronic part (6) to the board (7). As described above, the electrodes (6a, 6b) of the small-sized electronic part (6) is electrically connected to the circuit electrodes (7a, 7b) of the board (7) through the conduction path (5a) of the holder (1).
Note that, as described above, an operation of mounting the holder (1) accommodating the small-sized electronic part (6) to the mounting recess (8a) of the casing (8) is manually conducted most of the time, so utmost attention is essential for the operation.
In terms of the background of miniaturizing the mounting object apparatus of the small-sized electronic part (6) and miniaturizing the small-sized electronic part (6) itself, the inner edge of the pressing flange (4) of the conventional holder (1) is formed to be identical in shape with and to have a diameter smaller than those of the small-sized electronic part (6). That is, an attention is paid such that the pressing flange (4) engages with the small-sized electronic part (6), whereby the small-sized electronic part (6) does not disengage from the holder (1). However, as shown in FIG. 12, in the case of mounting the holder (1) to the mounting recess (8a), when the holder (1) is rubbed against an inner peripheral surface of the mounting recess (8a) while being pushed therein, the pressing flange (4) is rolled up in its partial or entire periphery, thereby releasing the engagement with the small-sized electronic part (6). In this state, when the holder (1) is accommodated in the mounting recess (8a) and is combined with the board (7), the small-sized electronic part (6) cannot be pressed at a portion where the pressing flange (4) is rolled up. Further, when the pressing flange (4) is rolled up in its entire periphery, there is a fear in that the small-sized electronic part (6) cannot be held in press contact with the conduction path (5a) of the holder (1), thereby being spaced apart from the conduction path (5a). In both cases, pressure with respect to the small-sized electronic part (6) is uneven, thereby causing a fear of a contact failure due to an unstable electrical connection of the electric connector portion (5) through the conduction path (5a).